1. Field of the Invention
The present invention relates to a device for comminuting the components of a stream of materials and in particular waste products, wherein the device comprises rotating blades and stationary blades (bed blades, stator blades) between which the comminution is accomplished, and a screen device through which the comminuted components are discharged.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Commercial waste, industrial waste, domestic waste etc., e.g. (hard) plastics, textiles, composites, rubber or scrap wood (such as pallets and particle boards) must be comminuted before they are definitively disposed of or in particular before they are returned to the cycle of valuable substances. For the comminution, single- or dual-shaft comminutors are known in prior art, which are charged, for example, by wheeled loaders, fork lifts or belt conveyors via a hopper for feeding material.
A central element of a conventional comminutor is a rotor unit which comprises a rotor equipped with blades which can be provided e.g. with concavely ground circular cutting crowns. The blades are fastened to blade holders, for example by screwing, which are welded into blade recesses or can be screwed, for example, the recesses being milled into the rotor. The comminution of the fed material is accomplished between the blades rotating together with the rotor and stationary, i.e. non-rotating, bed blades (stator blades, wiper elements).
The fed material can be pressed towards the rotating rotor by a load-controlled pushing device. After the material has been comminuted between the rotating blades and the bed blades, it is discharged through a screen device which determines the factor of comminution according to the mesh size and conveyed further by means of a conveying belt, a spiral conveyor, a chain conveyor or an exhaust system. The screen device can comprise a screen basket with several screen segments, for example with a mesh size of 5 to 150 mm.
The rotating blades as well as the stator blades are subject to extreme wear and therefore have to be turned or replaced after a certain operating time. Equally, the screens must be replaced at regular intervals. In general, the blades mounted on the rotor can be relatively easily turned with just a few adjustments (up to eight times) until they have to be replaced. A typical operating period for the stator blades is 50 to 500 hours. In prior art, two variants of attaching the stator blades with the corresponding maintenance methods involved are well-known.
On the one hand, the stator blades can be fastened together with the screens to a swing-out wall that can be swung upwards. The stator blades are turned or replaced in the swung-out state of the swing-out wall and thus in overhead work, as the swing-out wall must be swung out at overhead height. The overhead work at the heavy stator blades and fastening parts with individual weights of up to 25 kg is troublesome and dangerous and involves relatively long set-up times during which the comminutor cannot be operated. Moreover, the machine rigidity is reduced as the seat of the stator blades cannot be welded to the housing in this variant.
According to an alternative construction, however, the seat of the stator blades is firmly fixed to the machine housing. However, for the maintenance of the stator blades, a mechanic must either descend to the cutting space via the rotor and work at the stator blades in constricted space conditions, which involves a lot of time, or he must perform the required maintenance tasks again overhead after having opened an opening for maintenance in the housing wall.
As the downtime of the comminutor should be minimized for economic reasons, it is desirable to develop a mounting structure for the stator blades which permits a faster and safer maintenance, in particular a facilitated disassembly of worn-out stator blades and the assembly of new stator blades.